| Description |
Following in the footsteps of ISO, recent observations with Spitzer have revealed a population of galaxy systems which emit a huge amount of luminosity in their pure rotational mid-IR molecular hydrogen lines, in some cases reaching 10-30 percent of the bolometric luminosity. These large line-luminosities are believed to be powered by galactic-scale shocks, which efficiently transfer kinetic energy to smaller dense clouds in the turbulent post-shock medium. However, nothing at all is known about the other important cooling channels for the shocked gas, such as [OI], H2O, OH, and CO, some of which can rival H2 as a coolant. We propose deep PACS and SPIRE spectroscopy of the Giant Shock in Stephan.s Quintet and the Taffy Galaxy bridge to quantify the most important cooling channels and determine the physical state of the gas being shocked. The results have implications for understanding the importance of molecular cooling at higher redshift where turbulence and shock-heating may play a role in galaxy formation. |
